Several bacterial sensory-kinase receptors form clusters on the cell membrane. However, the dynamics of sensory-kinase clustering are largely unclear. Using measurements of fluorescence anisotropy and time-lapse imaging of Escherichia coli cells, we demonstrate that copper ions trigger self-association of BaeS receptors and lead to rapid formation of clusters, which can be reversibly dispersed ...

The relationship between formation of active in-line attack conformations and monovalent (Na(+)) and divalent (Mg(2+)) metal ion binding in hammerhead ribozyme (HHR) has been explored with molecular dynamics simulations. To stabilize repulsions between negatively charged groups, different requirements of the threshold occupancy of metal ions were observed in the reactant and activated precursor...

We have investigated the interaction of divalent ions with chromatin towards a closer understanding of the role of metal ions in the cell nucleus. The first row transition metal ion chlorides MnCl2, CoCl2, NiCl2 and CuCl2 lead to precipitation of chicken erythrocyte chromatin at a significantly lower concentration than the alkali earth metal chlorides MgCl2, CaCl2 and BaCl2. A similar distincti...

The catalytic (C) subunit of cAMP-dependent protein kinase (cAPK) is more stable by several criteria when it is part of a holoenzyme complex. By measuring the thermal stability of the free C subunit in the presence and absence of nucleotides and/or divalent metal ions, it was found that most of the stabilizing effects associated with the type I holoenzyme could be attributed to the nucleotide. ...

Beef heart mitochondrial ATPase (F1) catalyzes the hydrolysis of the ATP analog adenyl-5-yl imidodiphosphate (AMP-PNP). The reaction products are inorganic phosphate and adenyl-5-yl phosphoramidate (AMP-PN) as determined by HPLC analysis. The hydrolysis occurs in both the presence and absence of added divalent metal ions and is stimulated by potassium. The kinetic properties of the hydrolytic r...

The specificities of phosphate donors and the effects of metal chelating agents and divalent metal ions on NAD kinase activation by phytochrome-far red-absorbing form (Pfr) were examined. ATP was the most efficient phosphorylating agent. Uridine 5'-triphosphate, cytidine 5'-triphosphate (CTP), inosine 5'-triphosphate, and guanosine 5'-triphosphate in this order caused significant phosphorylatio...

Cation-assisted interactions between N-containing heterocycles (NHCs) and CO2 have been systematically studied by using density functional theory (DFT). For neutral and anionic (non-carbenoid) NHCs, the effects of monovalent cations (i.e., alkali metal ions) are moderate to small (the NHC-CO2 binding energy change, ΔBE usually < 25 kJ mol(-1)). However, for NHC carbenes, due to their strong bas...

Although the hammerhead ribozyme is regarded as a prototype for understanding RNA catalysis, the mechanistic roles of associated metal ions and water molecules in the cleavage reaction remain controversial. We have investigated the catalytic potential of observed divalent metal ions and water molecules bound to a 2 A structure of the full-length hammerhead ribozyme by using X-ray crystallograph...

The PspGI restriction-modification system recognizes the sequence CCWGG. R.PspGI cuts DNA before the first C in the cognate sequence and M.PspGI is thought to methylate N4 of one of the cytosines in the sequence. M.PspGI enhances fluorescence of 2-aminopurine in DNA if it replaces the second C in the sequence, while R.PspGI enhances fluorescence when the fluorophore replaces adenine in the cent...

Vitamin K deficiency or administration of vitamin K antagonists results in the biosynthesis of abnormal des-’y-carboxy forms of the vitamin K-dependent proteins. Monoclonal antibody H-i 1 binds several vitamin K-dependent proteins at a determinant that includes the first two residues of ‘y-carboxyglutamic acid. Antibody H-i 1 binds fully carboxylated prothrombin and protein C in the presence of...